It is often necessary to measure the depth of water as required by enviromental consideration. For example, an oil well drilled in an area or mining taking place in a location must not disturb, in many occasions, the surface waters of the region. In order to establish that the surface waters are unchanged, it is often necessary to measure the depth of the existing water level in existing holes or holes bored into the surface of the earth for accomplishing the test. A probe is dropped into the hole with the line supporting the probe having marks on the line indicating the depth of the probe in the hole. Once the probe strikes the water, the indicator should indicate the presence of the water. When the probe is withdrawn from the surface of the water, the indicator should indicate this fact. Measurements are made on several locations over the surface of the earth to determine the variations in water level as a consequence of the work being done in the area to establish that either there has been no change as a consequence of the work or to assess the amount of change if some did occur.